regex - CodeIgniter htaccess not redirecting to WWW

Question

my CI htaccess not redirecting from non www to www...

    RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_URI} ^system.*
RewriteRule ^(.*)$ index.php?/$1 [L]

RewriteCond %{REQUEST_URI} ^application.*
RewriteRule ^(.*)$ /index.php?/$1 [L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]

RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L] 


<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$">
Header set Cache-Control "max-age=604800, public"
</FilesMatch>

where is the problem? Also it should not remove params which is working now (index.php/ removing)

Answer 1

更改规则的顺序：

RewriteEngine On
RewriteBase /

RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI}  [R=301,L] 

RewriteCond %{REQUEST_URI} system|application
RewriteRule ^(.*)$ index.php?/$1 [L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]

<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$">
   Header set Cache-Control "max-age=604800, public"
</FilesMatch>